Charged particle detectors based on thin single crystal diamond films (3.0×3.0×0.09mm3) grown by chemical vapour deposition (CVD) technique are developed at Ruđer Bošković Institute and low field ...mobility, transit time and saturation velocity, measured by using a 210Po alpha source in vacuum at room temperature, are presented.
The comparison of the charge transport properties obtained by time of flight (ToF) technique between detectors based on the same diamond samples, but with different metallization of the electrodes (Au and Al, 100nm thick), and commercially purchased diamond detectors is performed.
The fabricated diamond sensors showed a spectroscopic resolution of up to 1%, mobility up to 1808±16 and 1914±71cm2/Vs for electrons and holes respectively and carrier transit time below 2ns for an applied electric field of 17.8×103V/cm. Results also show variations of the charge transport properties according to the electrode metallization used and the different modality at which the detectors are irradiated.
•- Possibility of using the diamond sensors also under condition of illumination and in air.•- Variation of the electronic properties of the charge carriers according to the different mode of irradiation.•- Variation of the electronic properties of the charge carriers according to the type of electric contacts adopted.•- Thin sensors report better spectroscopic performances compared to devices made of thick diamond samples.
Abstract The Super-FRS at the FAIR accelerator complex will adopt Chemical Vapor Deposition diamond detectors as radiation-hard particle rate counters. Their role will be to monitor the beam ...transmission for beams with ions rates up to 10 7 ions/spill and to calibrate the other beam diagnostics devices that are in duty at higher beam intensities. The target vacuum chamber of the Super-FRS hosts a 7 × 7 mm 2 single crystal diamond and a 25 × 25 mm 2 polycrystalline diamond: they are required to detect crossing particles with high efficiency (> 98%) in the case of heavy ion species (Ar to U), and to stand for several years in an environment in which they can potentially accumulate a dose of a few MGy per year. Laboratory measurements and beam test campaigns were arranged in the past years for the validation of the proposed sensors, in particular for the case of the polycrystalline technology. Here we report the outcome of the irradiation of a sensor based on a 20 × 20 mm 2 polycrystalline diamond produced by Element Six, with high intensity 1 GeV/nucleon Pb and U beams at GSI (Darmstadt). The detector signal shape characteristics and the ion counting efficiency have been monitored by interleaving periods of low ions rates, to evaluate possible damages or performance degradation during and after a total bombardment of about 6 × 10 11 heavy ions.
The kinetics of bacteriochlorophyll fluorescence in intact cells of the purple nonsulfur bacterium
Rhodobacter sphaeroides
were measured under continuous and pulsed actinic laser diode (808 nm ...wavelength and maximum 2 W light power) illumination on the micro- and millisecond timescale. The fluorescence induction curve was interpreted in terms of a combination of photochemical and triplet fluorescence quenchers and was demonstrated to be a reflection of redox changes and electron carrier dynamics. By adjustment of the conditions of single and multiple turnovers of the reaction center, we obtained 11 ms
–1
and 120 μs
–1
for the rate constants of cytochrome
c
2
3+
detachment and cyclic electron flow, respectively. The effects of cytochrome
c
2
deletion and chemical treatments of the bacteria and the advantages of the fluorescence induction study on the operation of the electron transport chain
in vivo
were discussed.
This paper investigates the characteristics and the metrological limits of the calibration of spring type gravimeters by using a cylindrical test mass moved vertically around the gravimeter by a ...lifting device operated in the Mátyáshegy Observatory. The movement of the 3100 kg iron mass generates a sinusoid-like calibrating signal having a peak-to-peak amplitude of 1102 nm s−2. The careful determination of the geometrical and physical parameters of the test mass combined with the analytical modeling of its gravitational effect and the related uncertainties provides an accuracy of 3 nm s−2 in absolute sense. The overall accuracy, however, is influenced by several other instrumental and environmental factors which are investigated in detail. The conclusions are based on more than 400 experiments with 5 LCR G instruments. As a unique case a Scintrex CG-5 instrument was also involved in the tests what is probably the very first moving mass calibration of this type of gravimeters. Two processing methods, Max-Min and Full-Fit, based on L2 norm adjustment of the observations were developed and applied to obtain instrumental scale factor and other related parameters. The results show that the observations corrected for the disturbing effects still contain a systematic constituent with amplitude of (10-20) nm s−2 regardless which LCR instrument was calibrated. It resembles the second time derivative of the calibrating signal that may indicate the non-uniform elastic response of the spring sensors to the rate of gravity change. Due to the problems mentioned above the overall dispersion of the resultant random and non-random residuals of the calibration observations provided by Full-Fit method are typically 10 nm s−2. The a posteriori standard deviations of the individual scale factors provide, however, measurement accuracy of 2 nm s−2.
Using the large acceptance apparatus FOPI, we study central collisions in the reactions (energies in A GeV are given in parentheses): 40Ca + 40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 58Ni + 58Ni (0.15, ...0.25, 0.4), 96Ru + 96Ru (0.4, 1.0, 1.5), 96Zr + 96Zr (0.4, 1.0, 1.5), 129Xe + CsI (0.15, 0.25, 0.4), 197Au + 197Au (0.09, 0.12, 0.15, 0.25, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include cluster multiplicities, longitudinal and transverse rapidity distributions and stopping, and radial flow. The data are compared to earlier data where possible and to transport model simulations.
Background and Objectives: The rate of head and neck cancer (HNC) is expected to increase by 30% by 2030. However, there are many similarities between the symptomatology of a benign and a malign ...diagnosis; thus, a protocol for conducting a full head and neck examination is of high importance since the absence of adenopathy does not exclude a malignant diagnosis and also a favorable prognosis. Material and methods: The current study presents a retrospective study on 515 adult patients who underwent a biopsy for possible head and neck tumor pathology. Results: The patients identified with cancer were older than the rest of the group, with a higher developing trend in men than in women. However, the top 10 symptomatology patterns were identical in the malign and benign groups, meaning that new HNC may be missed due to the common symptomatology between benign and malign outcomes. Conclusions: The importance of a full ear, nose, and throat (ENT) examination may be of significant relevance for a proper diagnosis that can improve the overall prognosis of a patient with cancer. The absence of routine screening tests and screening guidelines for oral and pharyngeal cancers represents a significant barrier to secondary HNC prevention.
The development of photosynthetic membranes of intact cells of Rhodobacter sphaeroides was tracked by light-induced absorption spectroscopy and induction and relaxation of the bacteriochlorophyll ...fluorescence. Changes in membrane structure were induced by three methods: synchronization of cell growth, adjustment of different growth phases and transfer from aerobic to anaerobic conditions (greening) of the bacteria. While the production of the bacteriochlorophyll and carotenoid pigments and the activation of light harvesting and reaction center complexes showed cell-cycle independent and continuous increase with characteristic lag phases, the accumulation of phospholipids and membrane potential (electrochromism) exhibited stepwise increase controlled by cell division. Cells in the stationary phase of growth demonstrated closer packing and tighter energetic coupling of the photosynthetic units (PSU) than in their early logarithmic stage. The greening resulted in rapid (within 0–4 h) induction of BChl synthesis accompanied with a dominating role for the peripheral light harvesting system (up to LH2/LH1 ~2.5), significantly increased rate (~7·10⁴ s⁻¹) and yield (F ᵥ/F ₘₐₓ ~0.7) of photochemistry and modest (~2.5-fold) decrease of the rate of electron transfer (~1.5·10⁴ s⁻¹). The results are discussed in frame of a model of sequential assembly of the PSU with emphasis on crowding the LH2 complexes resulting in an increase of the connectivity and yield of light capture on the one hand and increase of hindrance to diffusion of mobile redox agents on the other hand.
Low Gain Avalanche Detector (LGAD) technology has been used to design and construct prototypes of time-zero detector for experiments utilizing proton and pion beams with High Acceptance Di-Electron ...Spectrometer (HADES) at GSI Darmstadt, Germany. LGAD properties have been studied with proton beams at the COoler SYnchrotron facility in Jülich, Germany. We have demonstrated that systems based on a prototype LGAD operated at room temperature and equipped with leading-edge discriminators reach a time precision below 50 ps. The application in the HADES, experimental conditions, as well as the test results obtained with proton beams are presented.
The Time Of Flight (TOF) subsystem is one of the main detectors of the CBM experiment. The TOF wall in conjunction with Silicon Tracking System (STS) is foreseen to identify charged hadrons, i.e. ...pions, kaons and protons, with a full azimuthal coverage at 2.50 - 250 polar angles. A system time resolution of at least 80 ps, including all contributions, such as electronics jitter and the resolution of the time reference system, is required. Such a performance should be maintained up to a counting rate larger than 30 kHz/cm2 at the most inner region of TOF wall. Our R&D activity has been focused on the development of two-dimensional position sensitive Multi-gap Resistive Plate Counter (MRPC) prototypes for the forward region of the CBM-TOF subdetector, the most demanding zone in terms of granularity and counting rate. The in-beam tests using secondary particles produced in 30 GeV/u Pb ion collisions on a Pb target at SPS - CERN aimed to test the performance of these prototypes in conditions similar to the ones expected at SIS100 at FAIR. The performance of the prototypes is studied in conditions of exposure of the whole active area of the chamber to high multiplicity of reaction products. The results show that this type of MRPC fulfill the challenging requirements of the CBM-TOF wall. Therefore, such an architecture is recommended as basic solution for CBM-TOF inner zone.
The present work reports on a long-term irradiation test performed on a 0.3-mm thick polycrystalline diamond detector prototype. The device, biased at 300 V, was continuously irradiated for about ...60 h by using a 12C beam at 62 MeV/nucl. at the LNS-INFN Cyclotron facility in Catania. An ionization chamber, calibrated using a single crystal diamond detector, was used to evaluate the total absorbed dose in the diamond detector under study. Data analysis carried out on recorded oscilloscope waveforms shows no significant variation of the signal properties in terms of amplitude, slope and charge after exposure to an integrated flux of 6.2⋅ 1013 ions/cm2. The results indicate that a polycrystalline diamond detector can be used for calibrating intensity monitors at the future superconducting fragment separator Super-FRS at FAIR (Darmstadt).
•No change observed in the signal proprieties of an irradiated pcCVD diamond material•Diamond detectors as precise intensity monitors with heavy ion beams•Survival of a pcCVD diamond detector after long-term beam current calibrations
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